diff --git a/api/ovdashboard_api/__init__.py b/api/ovdashboard_api/__init__.py
index 4fa6c6e..edeb9eb 100644
--- a/api/ovdashboard_api/__init__.py
+++ b/api/ovdashboard_api/__init__.py
@@ -48,5 +48,6 @@ _CALDAV_CLIENT = caldav.DAVClient(
 )
 
 
+@run_in_executor
 def caldav_principal() -> caldav.Principal:
     return _CALDAV_CLIENT.principal()
diff --git a/api/ovdashboard_api/routers/_common.py b/api/ovdashboard_api/routers/_common.py
index 9c36bd1..b6f47f7 100644
--- a/api/ovdashboard_api/routers/_common.py
+++ b/api/ovdashboard_api/routers/_common.py
@@ -5,7 +5,7 @@ from typing import Iterator, Protocol
 from fastapi import HTTPException, status
 from webdav3.exceptions import RemoteResourceNotFound
 
-from .. import webdav_list
+from .. import caldav_principal, webdav_list
 from ..dav_file import DavFile
 
 
@@ -34,6 +34,17 @@ class FileNameLister:
             return iter(())
 
 
+@dataclass(frozen=True)
+class CalendarNameLister:
+    async def __call__(self) -> Iterator[str]:
+        principal = await caldav_principal()
+
+        return (
+            cal.name
+            for cal in principal.calendars()
+        )
+
+
 @dataclass(frozen=True)
 class PrefixFinder:
     lister: NameLister
diff --git a/api/ovdashboard_api/routers/calendar.py b/api/ovdashboard_api/routers/calendar.py
index 00e545a..85493cb 100644
--- a/api/ovdashboard_api/routers/calendar.py
+++ b/api/ovdashboard_api/routers/calendar.py
@@ -4,46 +4,31 @@ from typing import Iterator
 from fastapi import APIRouter, Depends, HTTPException, status
 
 from .. import caldav_principal
+from ._common import CalendarNameLister, PrefixFinder
 
 router = APIRouter(prefix="/calendar", tags=["calendar"])
 
-
-async def get_calendar_names() -> Iterator[str]:
-    principal = caldav_principal()
-    return (
-        cal.name
-        for cal in principal.calendars()
-    )
+_lister = CalendarNameLister()
+_finder = PrefixFinder(_lister)
 
 
 @router.get("/list", response_model=list[str])
 async def list_calendars(
-    calendar_names: Iterator[str] = Depends(get_calendar_names),
+    calendar_names: Iterator[str] = Depends(_lister),
 ) -> list[str]:
     return list(calendar_names)
 
 
-async def find_calendars_by_prefix(
-    prefix: str,
-    calendar_names: Iterator[str] = Depends(get_calendar_names),
-) -> Iterator[str]:
-    return (
-        name
-        for name in calendar_names
-        if name.lower().startswith(prefix.lower())
-    )
-
-
 @router.get("/find/{prefix}", response_model=list[str])
 async def find_calendars(
-    calendar_names: Iterator[str] = Depends(find_calendars_by_prefix),
+    calendar_names: Iterator[str] = Depends(_finder),
 ) -> list[str]:
     return list(calendar_names)
 
 
 @router.get("/get/{prefix}", response_model=list[str])
 async def get_calendar(
-    calendar_names: Iterator[str] = Depends(find_calendars_by_prefix),
+    calendar_names: Iterator[str] = Depends(_finder),
 ) -> list[str]:
     calendar_names = list(calendar_names)
 
@@ -53,7 +38,8 @@ async def get_calendar(
     elif len(calendar_names) > 1:
         raise HTTPException(status_code=status.HTTP_409_CONFLICT)
 
-    calendar = caldav_principal().calendar(name=calendar_names[0])
+    principal = await caldav_principal()
+    calendar = principal.calendar(name=calendar_names[0])
 
     events = calendar.date_search(
         start=datetime.now(),
diff --git a/api/ovdashboard_api/routers/image.py b/api/ovdashboard_api/routers/image.py
index f6c7283..9dbd568 100644
--- a/api/ovdashboard_api/routers/image.py
+++ b/api/ovdashboard_api/routers/image.py
@@ -7,7 +7,7 @@ from fastapi.responses import StreamingResponse
 from PIL import Image
 
 from ..dav_file import DavFile
-from ._common import FileNameLister, FilePrefixFinder, FilePrefixLoader
+from ._common import FileNameLister, FilePrefixLoader, PrefixFinder
 
 router = APIRouter(prefix="/image", tags=["image"])
 
@@ -19,7 +19,7 @@ _lister = FileNameLister(
     ),
 )
 
-_finder = FilePrefixFinder(_lister)
+_finder = PrefixFinder(_lister)
 _loader = FilePrefixLoader(_finder)
 
 
diff --git a/api/ovdashboard_api/routers/text.py b/api/ovdashboard_api/routers/text.py
index ad5f45d..7229a6f 100644
--- a/api/ovdashboard_api/routers/text.py
+++ b/api/ovdashboard_api/routers/text.py
@@ -6,7 +6,7 @@ from markdown import markdown
 
 from ..config import SETTINGS
 from ..dav_file import DavFile
-from ._common import FileNameLister, FilePrefixFinder, FilePrefixLoader
+from ._common import FileNameLister, FilePrefixLoader, PrefixFinder
 
 router = APIRouter(prefix="/text", tags=["text"])
 
@@ -18,7 +18,7 @@ _lister = FileNameLister(
     ),
 )
 
-_finder = FilePrefixFinder(_lister)
+_finder = PrefixFinder(_lister)
 _loader = FilePrefixLoader(_finder)